Problem: In the right triangle shown, $AC = 6$ and $BC = 7$. What is $AB$ ? $A$ $C$ $B$ $6$ $7$ $?$
We know $a^2 + b^2 = c^2$ We want to find $c$ ; let $a = 7$ and $b = 6$ So $c^2 = 7^2 + 6^2 = 85$ Then, $c = \sqrt{85}$.